In Next Generation Network (NGN) architecture, resource and admission control layer is introduced between service control layer and bearer transport layer, shielding transmission network details from the service layer and supporting the separation between service control function and transport function. The resource and admission control layer perceives the resource usage status of the transport network, and ensures that transport network resources are utilized correctly and rationally via admission control and resource control, so that Quality of Service (QoS) can be ensured, and moreover, bandwidth and service pirating can be avoided. As shown in FIG. 1, Resource and Admission Control Function (RACF) architecture standard is illustrated. In the architecture, the resource and admission control procedure includes the following. RACF may statically configure, or each bearer transport node may statically report topology and resource status (mainly available link bandwidth of each segment). When a service is established, the service layer requests transport resource (e.g., bandwidth) from the RACF. If the RACF finds that the resource is sufficient, then the RACF may admit the service request, and deduct a corresponding resource. If the RACF finds that the resource is insufficient, the admission is not allowed.
FIG. 2 illustrates a schematic diagram where admission control is accomplished by directly transmitting congestion information between an ingress node and an egress node in an on-demand manner in a Pre-Congestion Notification (PCN) network according to conventional arts. A PCN network usually includes ingress nodes, interior nodes and egress nodes, where the ingress nodes and the egress nodes are all edge nodes, and are distinguished by service flowing direction, that is, the direction of traffic. For a same edge node pair, A and B, assume that the direction of traffic is A→B, then A is the ingress node while B is the egress node; assume that the direction of traffic is B→A, then A is the egress node while B is the ingress node.
In a PCN network, the ingress node is generally responsible for conducting the admission control decision entity on data traffic entering the PCN domain, where the admission control decision may depend on a congestion status from the ingress node to the corresponding egress node. In a PCN network, the interior node is responsible for monitoring link traffic. When an interior node finds an upcoming congestion (traffic crosses a pre-congestion threshold) on a link connected therewith, then a receiving message is marked (with a pre-congestion mark). The egress node measures traffic that belongs to the same ingress node, where a weighed ration of traffic with pre-congestion mark to all of traffic from the ingress node is usually measured as a congestion degree, that is, Congestion Level Estimate (CLE). Next, the CLE is carried in a signaling message and transferred to the ingress node. In this way, the CLE represents a congestion status from the ingress to the egress, and accordingly, the ingress node may implement admission control decision based on the CLE.
Referring to FIG. 2, an existing admission control method may specifically include the followings.
1. A service traffic request arrives at an ingress node;
2. The ingress node queries a CLE from an egress node;
3. The egress node sends the current CLE to the ingress node;
4. The ingress node may determine whether to admit the service traffic request based on the acquired CLE. If the predetermined threshold is exceeded, the ingress node denies the service traffic request; if the predetermined threshold is not exceeded, the ingress node admits the service traffic request, and accordingly, switches on traffic control;
5. The ingress node notifies the service requestor of the result of the admission decision.
In implementing the present invention, it is discovered that the above conventional solution enmeasureers at least the following problems. The conventional admission control method is characterized in that, the egress node needs to transfer the CLE for each coming service traffic, thereby wasting signaling messages when the calling rate is very high.